title: Evidence of programmed cell death induced by reconditioning after cold stress in cucumber fruit and possible involvement of ethylene.
abstract: BACKGROUND
  Cucumber fruit is susceptible to chilling injury (CI), which could be accelerated significantly with subsequent shelf-life. This type of CI culminates in deterioration of organs and eventually leads to cell death. In this study, evidence of programmed cell death (PCD), involving cell death induced by cold stress, was investigated in cucumber. Harvested cucumber (Cucumis sativus L. cv. Zhexiu-1) fruits were stored at 2 °C for 3, 6 or 9 days and subsequently transferred to 20 °C for 2 days.
  
  
  RESULTS
  Significant cell death acceleration was observed upon reconditioning after 9 days' cold stress when the hallmark of PCD - DNA laddering - was clearly observed. Further evidence of nuclear DNA cleavage was confirmed by the in situ TdT-mediated dUTP nick end labeling (TUNEL) assay. Chromatin condensation and nucleus distortion were observed by nuclear staining of DPI. Ethylene burst was observed upon reconditioning after 9 days of consecutive cold stress.
  
  
  CONCLUSIONS
  The features of PCD process induced by reconditioning after cold stress in cucumber fruit may be mainly attributed to ethylene burst.
authors.affiliation: Department of Food Science and Nutrition, School of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, People's Republic of China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Chen
authors.forename: Peng
authors.initials: P
authors.lastname: Nie
authors.forename: Hongjun
authors.initials: H
authors.lastname: Deng
authors.forename: Hongbo
authors.initials: H
authors.lastname: Mi
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Hou
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Linchun
authors.initials: L
authors.lastname: Mao
mesh_terms: D017209:Apoptosis; D002467:Cell Nucleus / Q000378:metabolism; D053144:Cell Nucleus Shape; D002681:China; D042002:Chromatin Assembly and Disassembly; D003080:Cold Temperature / Q000009:adverse effects; D018553:Cucumis sativus / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D053938:DNA Fragmentation; D005030:Ethylenes / Q000378:metabolism*; D063427:Food Quality; D061353:Food Storage; D005638:Fruit / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D020287:In Situ Nick-End Labeling; D008856:Microscopy, Fluorescence; D019441:Plant Epidermis / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D005030:Ethylenes; C036216:ethylene
keywords: DNA ladder; cold stress; cucumber; ethylene; programmed cell death (PCD)